JPS5877679A - Ultrasonic measuring device for distance - Google Patents
Ultrasonic measuring device for distanceInfo
- Publication number
- JPS5877679A JPS5877679A JP17463881A JP17463881A JPS5877679A JP S5877679 A JPS5877679 A JP S5877679A JP 17463881 A JP17463881 A JP 17463881A JP 17463881 A JP17463881 A JP 17463881A JP S5877679 A JPS5877679 A JP S5877679A
- Authority
- JP
- Japan
- Prior art keywords
- time
- pulse
- ultrasonic
- signal
- counting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/02—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems using reflection of acoustic waves
- G01S15/06—Systems determining the position data of a target
- G01S15/08—Systems for measuring distance only
- G01S15/10—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves
- G01S15/12—Systems for measuring distance only using transmission of interrupted, pulse-modulated waves wherein the pulse-recurrence frequency is varied to provide a desired time relationship between the transmission of a pulse and the receipt of the echo of a preceding pulse
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Acoustics & Sound (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、超音波を発信し、所定の時間原点より物体か
らの反射波あるいは透過波受信時刻までクロックパルス
を計数して経過時間を求め、経過時間に音速を乗するこ
とにより距離を測定する超音波距離測定装置に関するも
のである。DETAILED DESCRIPTION OF THE INVENTION The present invention emits ultrasonic waves, counts clock pulses from a predetermined time origin to the time when a reflected wave or transmitted wave is received from an object, calculates the elapsed time, and multiplies the elapsed time by the speed of sound. This invention relates to an ultrasonic distance measuring device that measures distance by
従来の超音波距離測定装置では、1回の超音波発信時刻
からそれに対する反射波あるいは透過波受信時刻までク
ロックパルスケ計数して経過時間を求めていた。また所
望の反射波あるいは透過波全抽出するにあたっては、時
間ゲート(超音波発信時から一定時間経過後、一定の時
間範囲内で受信されるパルスを抽出する機能)で抽出す
る方法をとっていた。In conventional ultrasonic distance measuring devices, the elapsed time is determined by counting clock pulses from the time when one ultrasonic wave is transmitted to the time when the reflected wave or transmitted wave is received. In addition, in order to extract all of the desired reflected or transmitted waves, a method was used to extract them using a time gate (a function that extracts pulses received within a certain time range after a certain period of time has elapsed since the ultrasonic wave was transmitted). .
従来の方法における問題点のひとつにつぎのことがあげ
られる。それは、クロックパルスの周期に伴なう距離測
定の誤差が大きいことである。すなわち、超音波発信時
から反射波あるいは透過波受信までの経過時間t。は、
クロックパルスの計数値nで表わすと第(1)式の如く
表わされる。第+11式はクロックパルス数の量子化に
よる不確定時間幅がクロックパルス周期ΔTに相当する
ことを示す。One of the problems with the conventional method is as follows. That is, there is a large error in distance measurement due to the period of the clock pulse. That is, the elapsed time t from the time of ultrasonic transmission to the reception of reflected waves or transmitted waves. teeth,
When expressed by the count value n of clock pulses, it is expressed as in equation (1). Equation +11 shows that the uncertain time width due to quantization of the number of clock pulses corresponds to the clock pulse period ΔT.
nΔT<1゜<(n+1)ΔT ・・・・・・・・
・(1)ただしnは整数である。nΔT<1゜<(n+1)ΔT・・・・・・・・・
-(1) However, n is an integer.
したがって、クロックパルス数nにクロックパルス周期
ΔTe乗じ−さらに音速v’6乗じて求める反射波ある
いは透過波の伝播距離tは、真っ値に対し第(2)式で
表わされる誤差Δt2有する。Therefore, the propagation distance t of the reflected or transmitted wave, which is obtained by multiplying the number n of clock pulses by the clock pulse period ΔTe and the speed of sound v'6, has an error Δt2 expressed by equation (2) with respect to the true value.
0くΔt<vΔT ・・・・・・・・・(
2)ちなみにクロ1ツクパルス周波数が32MH2,音
速が5900m/S (鉄中の縦波の場合)の時、第(
2)式で表わされる誤差は最大0.184mmになる。0kuΔt<vΔT ・・・・・・・・・(
2) By the way, when the clock pulse frequency is 32MH2 and the sound speed is 5900m/S (in the case of longitudinal waves in iron), the
The error expressed by equation 2) is 0.184 mm at maximum.
誤差を小さくするにはクロックパルスの周波ffe高く
すればよいが、通常のIC素子を組み合せた回路では取
り扱えるクロックパルスの周波数は32MH2程度が限
度である。In order to reduce the error, the frequency ffe of the clock pulse can be increased, but the frequency of the clock pulse that can be handled by a circuit combining ordinary IC elements is limited to about 32 MH2.
本発明の目的は、従来の装置での問題点を解決し、クロ
ックパルス周期で決まる測定距離の誤差を容易に小さく
できる超音波距離測定装置を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic distance measuring device that solves the problems with conventional devices and can easily reduce errors in measured distance determined by the clock pulse period.
本発明は、対象物体からの反射波または透過波全受信す
るごとにこれに同期して次のパルスを送出し、この動作
ヲ複数回くり返すことによってクロックパルスの計数時
間を長くすることにより距離の計測値の誤差を減少させ
るようにしたことを特徴とするものである。The present invention transmits the next pulse in synchronization with each received reflected wave or transmitted wave from the target object, and repeats this operation multiple times to increase the counting time of the clock pulse. The present invention is characterized in that the error in the measured value of is reduced.
以下、本発明全図面を用いて詳細に説明する。Hereinafter, the present invention will be explained in detail using all the drawings.
第1図及び第2図は本発明の詳細な説明するためのもの
で、第1図は超音波探触子1を用い、物体3からの反射
波を観測する場合を示している。すなわち、探触子1か
ら発信された超音波は、伝播径路2′f、通って物体3
に入射され、反射されて探触子1で受信される。1 and 2 are for explaining the present invention in detail, and FIG. 1 shows a case where a reflected wave from an object 3 is observed using an ultrasonic probe 1. FIG. That is, the ultrasonic wave emitted from the probe 1 passes through the propagation path 2'f and reaches the object 3.
is incident on the probe 1, reflected and received by the probe 1.
第2図は第1図の系に於る超音波発信パルスと物体から
の反射パルスの時間関係を示しており、Uはパルス振幅
、横軸は第2図aの発信パルス4aの立ち上り時刻全時
間原点とした経過時間全示す。本発明では、まず第2図
aの発信パルス4aに対し反射波パルス5aが受信され
ると、これに同期して第2図すの発信パルス4bが送出
され、反射波パルス5bが受信される。以下同様にして
同図c、dと順次、前の超音波発信パルスによって得ら
れた反射波パルス受信に同期して超音波パルスを発信す
る。一方同図aに示すすめの超音波パルス4aから同図
eに示すクロックパルス6t−カウントし、これは蟻後
の反射波パルス5dを受信するまで続けられる。Figure 2 shows the time relationship between the ultrasonic transmission pulse and the reflected pulse from the object in the system of Figure 1, where U is the pulse amplitude and the horizontal axis is the total rise time of the transmission pulse 4a in Figure 2a. Shows all elapsed time with time as the origin. In the present invention, first, when the reflected wave pulse 5a is received in response to the transmitted pulse 4a of FIG. 2a, the transmitted pulse 4b of FIG. 2 is sent out in synchronization with this, and the reflected wave pulse 5b is received. . Thereafter, in the same manner, ultrasonic pulses are sequentially transmitted as shown in c and d of the figure in synchronization with the reception of the reflected wave pulse obtained by the previous ultrasonic transmission pulse. On the other hand, the clock pulse 6t shown in the figure e is counted from the recommended ultrasonic pulse 4a shown in the figure a, and this is continued until the reflected wave pulse 5d after the ant is received.
この時のカウント数kNとし、超音波発信回数yk回と
する。この場合、1回の超音波発信から反射波パルス受
信までの時間t。は、クロックパルスカウント数、超音
波発信回数に2用いて第(3)式の如く表わされる。The number of counts at this time is kN, and the number of ultrasound transmissions is yk. In this case, the time t from one ultrasound transmission to the reception of a reflected wave pulse. is expressed as in equation (3) using 2 for the clock pulse count number and the number of ultrasound transmissions.
NΔT、/k<to < (N+1 )Δ’l’/k
・・・・・・(3)ただしΔTはクロックパルス周期
を示す。NΔT, /k<to<(N+1)Δ'l'/k
(3) However, ΔT indicates the clock pulse period.
この結果上式による伝播時間に音速v1f:乗じて求め
られる超音波の伝播距離tは、真の値に対し第(4)式
で表わされる誤差ΔLとなる。As a result, the propagation distance t of the ultrasonic wave obtained by multiplying the propagation time by the above formula by the sound velocity v1f: is an error ΔL expressed by formula (4) with respect to the true value.
Q <J t< V 、d ’l’/ k
・−・・・・・−・(41以上、第(4)式と第(2)
式金較べればわかるように、同じ周期ΔTのクロックパ
ルスを用いても、反射波パルスの受信に同期して超音波
パルスを発信することtくり返し、初めの超音波パルス
発信時刻から最後の反射波パルス発信までの経過時間を
測定することにより、測定時間の量子化誤差に起因する
距離測定誤差を超音波パルス発信回数に反比例して小さ
くすることができる。Q < J t < V, d'l'/k
・−・・・・・・−・(41 or more, formula (4) and formula (2)
As can be seen by comparing the equations, even if a clock pulse with the same period ΔT is used, the ultrasonic pulse is transmitted in synchronization with the reception of the reflected wave pulse. By measuring the elapsed time until the pulse is transmitted, it is possible to reduce the distance measurement error caused by the quantization error of the measurement time in inverse proportion to the number of times the ultrasonic pulse is transmitted.
次に、上述した本発明の原理にもとづく装置の実施例を
説明する。第3図は本発明の一実施例を示すブロック図
で、装置7は、探触子1にスパイク状電気パルスへを印
加する。この電気パルスAの印加は装置9より入力され
る発信指示パルスDに同期して行われる。探触子lは電
気パルスA7>f印加されると励振され、超音波パルス
を発信する。Next, an embodiment of the apparatus based on the principle of the present invention described above will be described. FIG. 3 is a block diagram showing an embodiment of the present invention, in which a device 7 applies spike-like electrical pulses to the probe 1. In FIG. The application of this electric pulse A is performed in synchronization with the transmission instruction pulse D input from the device 9. When the electric pulse A7>f is applied, the probe l is excited and emits an ultrasonic pulse.
探触子1で受信した超音波信号Bは装置8に入力される
。装置8では入力される超音波信号Bのうち超音波発信
より一定時間経過後の所定時間内の超音波パルスを抽出
し、そのうち予め定められたm番目のパルスのみを信号
Cとして出方する。これは、反射面が一般には複数個め
シ、そのどれを対象として測定するかを決めるためであ
る。装置9では、初めに発信指示パルスDを出力した後
は、信号Cに同期した発信指示パルスD’1k−1回装
置7に出力する。また初めに出力した発信指示パルスD
を信号Eとし、k回目の発信指示パルス出力後のパルス
信号Cを信号Fとしてそれぞれ装置lOに出力する。装
置110では、周期ΔTのクロックパルスの数を信号E
が入力されてから信号Fが入力されるまでカウントし、
そのカウント数ヲ装置11に出力する。装置11では第
(5)式にもとづき距1lItt算出して表示する。The ultrasonic signal B received by the probe 1 is input to the device 8. The device 8 extracts ultrasonic pulses within a predetermined time period after a certain period of time has elapsed from the ultrasonic wave transmission from the input ultrasonic signal B, and outputs only a predetermined m-th pulse among them as a signal C. This is because there are generally a plurality of reflective surfaces, and it is necessary to decide which one to measure. After first outputting the transmission instruction pulse D, the device 9 outputs the transmission instruction pulse D'1k-1 times synchronized with the signal C to the device 7. Also, the transmission instruction pulse D that was output at the beginning
is output as a signal E, and a pulse signal C after outputting the k-th transmission instruction pulse is output as a signal F to the device IO. In device 110, the number of clock pulses of period ΔT is determined by signal E.
Counts from when is input until signal F is input,
The count number is output to the device 11. The device 11 calculates and displays the distance 1lItt based on equation (5).
t=VNΔT/2k ・・・・・・・・・
(5)ただしVは音速、Nはカウント数、ΔTはクロッ
クパルス周期、には超音波発信回数を示し、tは探触子
と物体との距離金示す。t=VNΔT/2k ・・・・・・・・・
(5) where V is the speed of sound, N is the number of counts, ΔT is the clock pulse period, is the number of ultrasound transmissions, and t is the distance between the probe and the object.
信号A、B、C,D、E、Fのタイムチャート全それぞ
n時間軸を同じにして第4図に示す。信号Aはスパイク
状酸気印加パルスであり、発信指示パルスDに同期して
装置7より出力される。信号Bは探触子lの受信信号で
ある。信号Cに装置8によって信号Bから抽出した反射
波パルス信号を示す。すなわち、超音波発信時より一定
時間経過後所定の時間内(時間グー1囲Taとして図示
。)に受信した反射波パルスのうちm番目に受信した反
射波のみを抽出したことを示す。信号りは装置9より出
力される発信指示パルスを示し、第2回目以降第に回目
のパルスはパルス信号Cに同期して出力される。信号E
は第1回目の発信指示信号に同期して出力され、信号F
は第に回目の超音波発信で得られるパルス信号Cに同期
して出力される。The time charts of signals A, B, C, D, E, and F are all shown in FIG. 4 with the same time axes. Signal A is a spike-like acid gas application pulse, and is output from device 7 in synchronization with transmission instruction pulse D. Signal B is the received signal of probe l. Signal C shows the reflected wave pulse signal extracted from signal B by device 8. That is, it shows that only the m-th reflected wave received among the reflected wave pulses received within a predetermined time (illustrated as one time circle Ta) after a certain period of time has elapsed from the time of ultrasonic transmission is extracted. The signal C indicates a transmission instruction pulse outputted from the device 9, and the second and subsequent pulses are outputted in synchronization with the pulse signal C. Signal E
is output in synchronization with the first transmission instruction signal, and the signal F
is output in synchronization with the pulse signal C obtained in the first ultrasound transmission.
第5図は本発明の別の実施例全示し、第6図はその動作
波形である。第5図及び第6図で第3図及び第4図と同
一符号のものは同一の物または信号を表わしており、構
成上は装置81及び装置101が追加されている。FIG. 5 shows another embodiment of the present invention, and FIG. 6 shows its operating waveforms. In FIGS. 5 and 6, the same reference numerals as in FIGS. 3 and 4 represent the same objects or signals, and the device 81 and device 101 are added in the configuration.
このうち、装+181は装置8と同僚な機能を有し、探
触子1の受信信号Bのうち、超音波発信時より一定時間
経過後所定の時間内に受信した反射波パルスのうちm1
4目(但しm l(m )に受信した反射波パルスC1
のみを抽出して出力する。Of these, the device +181 has the same function as the device 8, and among the received signal B of the probe 1, m1 of the reflected wave pulses received within a predetermined time after a certain time elapsed from the time of ultrasonic transmission.
The reflected wave pulse C1 received at the 4th eye (m l (m)
Extract and output only.
装置101では、信号01人力時点からクロックパルス
dt−カウント開始し、信号C入力でカウントを停止す
ることをくり返す。信号Ft−装置9から入力されると
カウント数ヲ装置11に出力する。The device 101 repeatedly starts counting clock pulses dt from the point in time when the signal 01 is manually input, and stops counting when the signal C is input. When the signal Ft is input from the device 9, the count number is output to the device 11.
この時の各信号のタイムチャートが第6図に示されてい
る。A time chart of each signal at this time is shown in FIG.
第6図に示す如く、信号C1は、時間ゲート範囲Tcで
受信した反射波パルスのうちm1番目のパルスを抽出し
た信号である。信号C1に同期してクロックパルス数の
カラン)’51−開始し、信号Cに同期してカウント?
停止し以下カウント開始と停止をくり返すことは、m1
番目の反射波とm番目の反射波との伝播時間差金測定す
るのが目的である。したがって第5図に示す装置構成は
、第7図に示すような条件で、金属15の板厚、あるい
はg8図に示すように金属15の表面12から内部欠陥
14までの距fiffi測定するととができる。As shown in FIG. 6, the signal C1 is a signal obtained by extracting the m1th pulse from among the reflected wave pulses received in the time gate range Tc. Counting the number of clock pulses in synchronization with signal C1) '51-Start and count in synchronization with signal C?
Stopping and then repeating the start and stop of counting is m1.
The purpose is to measure the propagation time difference between the th reflected wave and the mth reflected wave. Therefore, the apparatus configuration shown in FIG. 5 can be used to measure the plate thickness of the metal 15 or the distance fiffi from the surface 12 of the metal 15 to the internal defect 14 as shown in FIG. can.
例えば第7図及び第8図の金属表面12からの反射波は
信号B中のm1番目のパルス、第7図の金属底面13ま
たは第8図の内部欠陥表面140反射波はB中のm番目
のパルスに設定すればよい。For example, the reflected wave from the metal surface 12 in FIGS. 7 and 8 is the m1th pulse in signal B, and the reflected wave from the metal bottom surface 13 in FIG. 7 or the internal defect surface 140 in FIG. The pulse should be set to .
以上の説明から明らかなように、本発明によれば、従来
装置と同じ周波数のクロックパルスを用いても、クロッ
クパルス計数における量子化誤差に起因する距離の測定
誤差を大幅に小さくすることができるという効果がある
。As is clear from the above description, according to the present invention, distance measurement errors caused by quantization errors in clock pulse counting can be significantly reduced even if clock pulses of the same frequency as conventional devices are used. There is an effect.
第1図は、距離測定における探触子と物体との配置及び
その時の超音波の伝播径路を示した図、第2図は、本発
明の原理説明図、第3図及びg4図は本発明の一実施例
及びその動作説明図、第5図及び第6図は本発明の他の
実施例及びその動作説明図、第7図及び第8図は第5図
の実施例の適用例を説明する図である。
1・・・探触子、7・・・発振手段、8.81・・・抽
出手段、9・・・同期化手段、10,101・・・計数
手段、11第 1 回
子 2 図Fig. 1 is a diagram showing the arrangement of a probe and an object in distance measurement and the propagation path of ultrasonic waves at that time, Fig. 2 is a diagram illustrating the principle of the present invention, and Figs. 3 and g4 are in accordance with the present invention. 5 and 6 are diagrams illustrating another embodiment of the present invention and its operation, and FIGS. 7 and 8 are diagrams illustrating an application of the embodiment shown in FIG. 5. This is a diagram. DESCRIPTION OF SYMBOLS 1... Probe, 7... Oscillation means, 8.81... Extraction means, 9... Synchronization means, 10, 101... Counting means, 11 1st circuit 2 Figure
Claims (1)
反射波るるいは透過波を受信するまでの経過時間を求め
て距dk測定する超音波距離測定装置に於て、超音波パ
ルスを周期的に発生する発振手段と、該手段からの超音
波パルスの発振後火の発振までの1周期内に設定された
ゲート時間内に受信された上記反射波あるいは透過波の
予め定められた順位のもののみを抽出する第1の抽出手
段と、該第1の抽出手段が上記反射波あるいは透過波を
抽出した時点に同期して上記発信手段から第2回目以後
の超音波パルスを予め定められた回数だけ発生せしめる
同期化手段と、上記周期毎に設定された計数時間内のク
ロックパルス数を上記各周期毎に積算して計数する計数
手段と、該手段の計数値から距#Iを算出する距離算出
手段とを備えたことを特徴とする超音波距離測定装置。 2、特許請求の範囲第1項記載の超音波距離測定装置に
於て、前記計数手段の計数時間會前記各周期そのものと
一致させたことを特徴とする超音波距離測定装置。 3、特許請求の範囲、@1項記載の超音波路AfI測定
装゛l!(於て、前記ゲート時間内に受信された前記反
射波あるいは透過波のうちの前記第1の抽出手段により
抽出されるものよりも時間的に早い一定;−位のものを
(2)出する第2の抽出手段を設けるとともに、前記計
数手段の計数時間を上記第2の抽出手段の出力時点から
上記5glの抽出手段の出力時点迄としたことを特徴と
する超音波距離測定装置。[Claims] 1. An ultrasonic distance measuring device that emits all ultrasonic pulses and measures the distance dk by determining the elapsed time from the time of transmitting the ultrasonic waves until receiving reflected or transmitted waves from an object. An oscillation means for periodically generating ultrasonic pulses, and the reflected wave or transmitted wave received within a gate time set within one cycle from the oscillation of the ultrasonic pulse to the oscillation of the flame from the oscillation means. a first extraction means for extracting only waves of a predetermined order; and a first extraction means for extracting only waves of a predetermined order; a synchronizing means for generating ultrasonic pulses a predetermined number of times; a counting means for accumulating and counting the number of clock pulses within a counting time set for each period; and a counting means for said means. An ultrasonic distance measuring device comprising distance calculating means for calculating distance #I from a numerical value. 2. The ultrasonic distance measuring device according to claim 1, wherein the counting time of the counting means is made to coincide with each of the periods themselves. 3. Claims: Ultrasonic path AfI measuring device as described in @1! (2) Output a certain - order earlier in time than the reflected wave or transmitted wave extracted by the first extraction means among the reflected waves or transmitted waves received within the gate time. An ultrasonic distance measuring device characterized in that a second extraction means is provided, and the counting time of the counting means is set from the output time of the second extraction means to the output time of the 5 gl extraction means.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17463881A JPS5877679A (en) | 1981-11-02 | 1981-11-02 | Ultrasonic measuring device for distance |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17463881A JPS5877679A (en) | 1981-11-02 | 1981-11-02 | Ultrasonic measuring device for distance |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS5877679A true JPS5877679A (en) | 1983-05-11 |
Family
ID=15982083
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP17463881A Pending JPS5877679A (en) | 1981-11-02 | 1981-11-02 | Ultrasonic measuring device for distance |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5877679A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4679175A (en) * | 1984-12-13 | 1987-07-07 | Honeywell Inc. | Ultrasonic distance sensor with dual burst noise rejection |
US4719605A (en) * | 1984-12-13 | 1988-01-12 | Honeywell Inc. | Self-calibrating ultrasonic range finder |
US4977778A (en) * | 1986-10-29 | 1990-12-18 | Movats Incorporated | Check valve testing system |
US5154080A (en) * | 1986-10-29 | 1992-10-13 | Westinghouse Electric Corp. | Integrated check valve testing system |
US5159835A (en) * | 1986-10-29 | 1992-11-03 | Westinghouse Electric Corp. | Check valve testing system |
WO2010142512A1 (en) * | 2009-06-12 | 2010-12-16 | Endress+Hauser Flowtec Ag | Measuring device and method for measuring a measurement variable |
-
1981
- 1981-11-02 JP JP17463881A patent/JPS5877679A/en active Pending
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4679175A (en) * | 1984-12-13 | 1987-07-07 | Honeywell Inc. | Ultrasonic distance sensor with dual burst noise rejection |
US4719605A (en) * | 1984-12-13 | 1988-01-12 | Honeywell Inc. | Self-calibrating ultrasonic range finder |
US4977778A (en) * | 1986-10-29 | 1990-12-18 | Movats Incorporated | Check valve testing system |
US5154080A (en) * | 1986-10-29 | 1992-10-13 | Westinghouse Electric Corp. | Integrated check valve testing system |
US5159835A (en) * | 1986-10-29 | 1992-11-03 | Westinghouse Electric Corp. | Check valve testing system |
WO2010142512A1 (en) * | 2009-06-12 | 2010-12-16 | Endress+Hauser Flowtec Ag | Measuring device and method for measuring a measurement variable |
US8881603B2 (en) | 2009-06-12 | 2014-11-11 | Endress + Hauser Flowtec Ag | Measuring device and method having superimposed reflected first measurement signal with a second measurement signal |
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